In a big glass bowl, add the peanut butter and chocolate. Microwave in 30 second increments, stirring after each until melted. Mine took about 1 minute and 15 seconds. Careful not to burn your chocolate.
Pour in the Chex cereal and stir with a spoon until everything is evenly coated. Add the protein powder and stir again until evenly coated. Alternatively, you could add the Chex to a big container with a lid and add the protein powder and shake until combined.
Enjoy! Store in an airtight container in the fridge.